Light emitting device and electronic appliance using the same

Abstract

A light emitting device comprises a pair of electrodes and a mixed layer provided between the pair of electrodes. The mixed layer contains an organic compound which contains no nitrogen atoms, i.e., an organic compound which dose not have an arylamine skeleton, and a metal oxide. As the organic compound, an aromatic hydrocarbon having an anthracene skeleton is preferably used. As such an aromatic hydrocarbon, t-BuDNA, DPAnth, DPPA, DNA, DMNA, t-BuDBA, and the like are listed. As the metal oxide, molybdenum oxide, vanadium oxide, ruthenium oxide, rhenium oxide, and the like are preferably used. Further, the mixed layer preferably shows absorbance per 1 μm of 1 or less or does not show a distinct absorption peak in a spectrum of 450 to 650 nm when an absorption spectrum is measured.

1. A light emitting device comprising:
 a first electrode; 
 a second electrode; 
 n light emitting layers formed between the first electrode and the second electrode; 
 a first mixed layer formed between an m-th light emitting layer of the n light emitting layers and an (m+1)-th light emitting layer of the n light emitting layers; and 
 a second mixed layer formed between the m-th light emitting layer and the (m+1)-th light emitting layer, 
 wherein n is a natural number of 2 or more and m is a natural number of 1 ≦m ≦n−1, 
 wherein the first mixed layer is provided to be closer than the second mixed layer to the first electrode, 
 wherein the first mixed layer contains a substance having an electron transporting property or a bipolar substance, and a substance selected from the group consisting of an alkali earth metal, an alkali metal oxide, an alkali earth metal oxide, an alkali metal fluoride, and an alkali earth metal fluoride, 
 wherein the second mixed layer contains an aromatic hydrocarbon and a metal oxide, 
 wherein the metal oxide is selected from the group consisting of molybdenum oxide, vanadium oxide, ruthenium oxide, and rhenium oxide, and 
 wherein the aromatic hydrocarbon is an anthracene derivative. 
 
     
     
       2. A light emitting device according to  claim 1 , wherein the aromatic hydrocarbon has 14 to 60 carbon atoms. 
     
     
       3. A light emitting device according to  claim 1 , wherein the anthracene derivative is any one of 2-tert-butyl-9,10-di(2-naphthyl)anthracene; 9,10-di(naphthalen-1-yl)-2-tert-butylanthracene; anthracene; 9,10-diphenylanthracene; 9,10-bis(3,5-diphenylphenyl)anthracene; 9,10-di(naphthalen-2-yl)anthracene; 2-ted-butylanthracene; 9,10-di(4-methylnaphthalen-1-yl)anthracene; 9,10-bis[2-(naphthalen-1-yl)phenynanthracene; 2,3,6,7-tetramethyl-9,10-di(naphthalen-1-yl)anthracene; 2,3,6,7-tetramethyl-9,10-di(naphthalen-2-yl)anthracene; bianthryl; 10,10′-di(2-phenylphenyl)-9,9′-bianthryl; 10,10′-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9′-bianthryl; and 9,10-di(4-phenylphenyl)-2-tert-butylanthracene. 
     
     
       4. An electronic appliance comprising the light emitting device according to  claim 1 . 
     
     
       5. A lighting device comprising the light emitting device according to  claim 1 . 
     
     
       6. A light emitting device according to  claim 1 , wherein the first electrode is an anode. 
     
     
       7. A light emitting device comprising:
 a first electrode; 
 a second electrode; 
 n light emitting layers formed between the first electrode and the second electrode; 
 a first mixed layer formed between an m-th light emitting layer of the n light emitting layers and an (m+1)-th light emitting layer of the n light emitting layers; and 
 a second mixed layer formed between the m-th light emitting layer and the (m+1)-th light emitting layer, 
 wherein n is a natural number of 2 or more and m is a natural number of 1≦m≦n−1, 
 wherein each of the n light emitting layers includes a light emitting substance and the light emitting substances are different from each other, 
 wherein the first mixed layer is provided to be closer than the second mixed layer to the first electrode, 
 wherein the first mixed layer contains a substance having an electron transporting property or a bipolar substance, and a substance selected from the group consisting of an alkali earth metal, an alkali metal oxide, an alkali earth metal oxide, an alkali metal fluoride, and an alkali earth metal fluoride, 
 wherein the second mixed layer contains an aromatic hydrocarbon and a metal oxide, 
 wherein the metal oxide is selected from the group consisting of molybdenum oxide, vanadium oxide, ruthenium oxide, and rhenium oxide, and 
 wherein the aromatic hydrocarbon is an anthracene derivative. 
 
     
     
       8. A light emitting device according to  claim 7 , wherein the aromatic hydrocarbon has 14 to 60 carbon atoms. 
     
     
       9. A light emitting device according to  claim 7 , wherein the anthracene derivative is any one of 2-tert-butyl-9,10-di(2-naphthyl)anthracene; 9,10-di(naphthalen-1-yl)-2-tert-butylanthracene; anthracene; 9,10-diphenylanthracene; 9,10-bis(3,5-diphenylphenyl)anthracene; 9,10-di(naphthalen-2-yl)anthracene; 2-tert-butylanthracene; 9,10-di(4-methylnaphthalen-1-yl)anthracene; 9,10-bis[2-(naphthalen-1-yl)phenyl]anthracene; 2,3,6,7-tetramethyl-9,10-di(naphthalen-1-yl)anthracene; 2,3,6,7-tetramethyl-9,10-di(naphthalen-2-yl)anthracene; bianthryl; 10,10′-di(2-phenylphenyl)-9,9′-bianthryl; 10,10′-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9′-bianthryl; and 9,10-di(4-phenylphenyl)-2-tert-butylanthracene. 
     
     
       10. A light emitting device according to  claim 7 , wherein the first electrode is an anode. 
     
     
       11. An electronic appliance comprising the light emitting device according to  claim 7 . 
     
     
       12. A lighting device comprising the light emitting device according to  claim 7 . 
     
     
       13. A light emitting device comprising:
 a first electrode; 
 a second electrode; 
 n light emitting layers formed between the first electrode and the second electrode; 
 a first mixed layer formed between an m-th light emitting layer of the n light emitting layers and an (m+1)-th light emitting layer of the n light emitting layers; and 
 a second mixed layer formed between the m-th light emitting layer and the (m+1)-th light emitting layer, 
 wherein n is a natural number of 2 or more and m is a natural number of 1≦m≦n−1, 
 wherein any of the n light emitting layers includes a host material and a light emitting substance dispersed in the host material, 
 wherein the first mixed layer is provided to be closer than the second mixed layer to the first electrode, 
 wherein the first mixed layer contains a substance having an electron transporting property or a bipolar substance, and a substance selected from the group consisting of an alkali earth metal, an alkali metal oxide, an alkali earth metal oxide, an alkali metal fluoride, and an alkali earth metal fluoride, 
 wherein the second mixed layer contains an aromatic hydrocarbon and a metal oxide, 
 wherein the metal oxide is selected from the group consisting of molybdenum oxide, vanadium oxide, ruthenium oxide, and rhenium oxide, and 
 wherein the aromatic hydrocarbon is an anthracene derivative. 
 
     
     
       14. A light emitting device according to  claim 13 , wherein the aromatic hydrocarbon has 14 to 60 carbon atoms. 
     
     
       15. A light emitting device according to  claim 13 , wherein the anthracene derivative is any one of 2-tert-butyl-9,10-di(2-naphthyl)anthracene; 9,10-di(naphthalen-1-yl)-2-tert-butylanthracene; anthracene; 9,10-diphenylanthracene; 9,10-bis(3,5-diphenylphenyl)anthracene; 9,10-di(naphthalen-2-yl)anthracene; 2-tert-butylanthracene; 9,10-di(4-methylnaphthalen-1-yl)anthracene; 9,10-bis[2-(naphthalen-1-yl)phenyl]anthracene; 2,3,6,7-tetramethyl-9,10-di(naphthalen-1-yl)anthracene, 2,3,6,7-tetramethyl-9,10-di(naphthalen-2-yl)anthracene; bianthryl; 10,10′-di(2-phenylphenyl)-9,9′-bianthryl; 10,10′-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9′-bianthryl; and 9,10-di(4-phenylphenyl)-2-tert-butylanthracene. 
     
     
       16. An electronic appliance comprising the light emitting device according to  claim 13 . 
     
     
       17. A light emitting device according to  claim 13 , wherein the first electrode is an anode. 
     
     
       18. A lighting device comprising the light emitting device according to  claim 13 .